Bearing defect frequencies
BPFO, BPFI, BSF and FTF from bearing geometry and shaft speed, with the harmonics and the minimum spectrum Fmax you need to see them.
Facilities & integrity
Relief valve orifice sizing (API 520)
Required orifice area for vapour or liquid relief, mapped onto the nearest API 526 standard orifice.
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How it is calculated
- Vapour, critical flow: A = W·√(TZ/M) / (C·Kd·P₁·Kb·Kc), with C = 520·√[k·(2/(k+1))^((k+1)/(k−1))].
- Liquid: A = Q·√(G/ΔP) / (38·Kd·Kw·Kc·Kv), the API 520 certified-valve form.
- Relieving pressure is set pressure × (1 + overpressure) + 14.7, in psia.
- The result is rounded up to the next API 526 designation, D through T.
Standards it speaks
Where this stops being true
Sizing is downstream of the question that actually matters, which is the relief load. Fire case, blocked outlet, tube rupture, thermal expansion and control-valve failure each give a different required flow, and this tool takes whichever one you type as given — a valve sized perfectly for the wrong scenario protects nothing. The vapour equation also assumes critical flow and a conventional spring-loaded valve; balanced-bellows and pilot-operated valves have different back-pressure behaviour, and two-phase or flashing relief needs the API 520 Part I Appendix D method, which this does not implement.
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